Forcing Bulbs

There may be a time in the upcoming winter that you yearn for spring fragrances and color before their time. Getting spring bulbs to flower indoors in the winter is called “forcing”. It’s fun to “fool Mother Nature” and potted spring bulbs make great gifts for the upcoming holidays.Normally a spring bulb is dormant in the winter. Shoot growth begins in the spring when temperatures rise. Flowering follows. In order to force a bloom you must mimicits natural pattern and expose it to cold (chill). Bulb varieties differ in their “chill” or dormancy requirements. A chill temperature is considered to be around 40º but length of time varies in plant varieties. Bulbs can be chilled in a bag in a refrigerator before planting or can be chilled in the pots you wish to grow them in. Place planted pots in a cool garage or cellar, or dig a trench in a shady area of your garden and cover with dried leaves, straw, or spaghnum moss. Dig up when ready to place inlight and “force” the bloom.

Some bulbs are more easily forced to bloom than others. Both paperwhite narcissus and amaryllis need no “chill time”. Other spring bulbs need more chill time. The elegant hyacinth can be forced in “hyacinth vases” using only water. They need 10–14 weeks of chill time then 2-3 more weeks to bloom. Small flowers such as the Muscari (grape hyacinth) and snowdrop can be clustered in pots. They need 13–16 weeks of chill. Siberian squill (Scilla siberica) need 15 weeks of chill as do some varieties of tulip. Once bulbs have completed their chill cycle, they are exposed to low light until their leaves turn green.

Finally, they can be placed in a sunny window where they “go into action”. If you are thinking of giving potted bulbs as holiday gifts, get them started now. Enclose a handwritten card with instructions on how the receiver can finish the process to enjoy spring blooms in the upcoming months.